PS4 Pro outputting PCM via LG CX shows Multichannel PCM 7.1 for Sonos Arc, but rear surrounds have no audio


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I have the Arc, Sub, and Sonos 1 in a surround setup, connected to an LG CX via eArc. Previously I had the PS4 outputting Bitstream (Dolby), and Sonos reported Dolby Digital 5.1.

The fix that added LPCM to Sonos Arc recently went live, so I updated PS4 Pro to output PCM, and the HDMI input on the TV to PCM. (The output remained Passthrough). After doing this, the System Status page for Sonos shows Multichannel PCM 7.1.

However, I now get no rear surround audio in games like Assassin’s Creed Valhalla. (It’s not faint, there’s really none.) I get the full surround experience if I change it back to getting Dolby Digital 5.1. On the PS4 Home screen, I do get sound from the rears in PCM 7.1, albeit very faintly, compared to Dolby Digital 5.1.

Does Sonos not downmix the extra channels properly? It’s kinda bad that a higher fidelity signal sounds worse.


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Wow, this is taking a long time to fix. You would think this is trivial since downmixing is something that has been around for a long time. Should be not really a problem for a company that has, I suspect,  lots of audio experts. Don’t get me wrong. I’m heavily invested in Sonos, and I have no other choice than to wait. I’m just really surprised this was even missed in the first placed when launching the Arc. 

I couldn’t have said it better myself. And I believe it was said that a fix would be anticipated this past July. A shame. I love my speakers; but I expect better.

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Wow, this is taking a long time to fix. You would think this is trivial since downmixing is something that has been around for a long time. Should be not really a problem for a company that has, I suspect,  lots of audio experts. Don’t get me wrong. I’m heavily invested in Sonos, and I have no other choice than to wait. I’m just really surprised this was even missed in the first placed when launching the Arc. 

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I emailed their CEO earlier today and received a response back from one of their senior software engineers 

 

“Patrick forwarded your Email concerning LPCM down-mix issues and I can give you an update on that. The engineering team is currently working on the issue as we speak. There are two steps here, one is to correct the downmixing in the case where there are no discrete surrounds and the other is when there are discrete surrounds. We have completed the first step and we are testing the fix and now working on the second step.

 

At this time I am unable to give you an exact date for availability of the SW fix but know that we are addressing it and when I know more, I will let you know.”

 

 

Hopefully it’s not that far away

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Hi All.

As mentioned previously, this is an issue we’re aware of.

Currently, Sonos does support multichannel LPCM in 5.1 mode on the Arc, but does not support multichannel LPCM in 7.1 mode - Downmixing LPCM 7.1 to 5.1 is a feature we are currently working on, however; we do not have any further information to share with you at this time. Rest assured, we will address this in a forthcoming update.

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LG CX and PS5 with Sonos Arc here. I’m using the settings below and getting some pretty solid sound with Dolby Multichannel PCM 5.1. So far any other setting results in Stereo PCM 2.0 and sounds worse. I know it’s not LPCM, but so far I can’t get anything else to work.

 

LG CX:

HDMI Input Audio Format: Bitstream

Digital Sound Out: Auto

PS5: 

Audio Format (Priority): Bitstream (Dolby)

HDMI Device Type: AV Ampoifier

Number of Channels: 5.1ch

 

 

The thing is Sonos clearly needs to fix a few bugs here. First of all there is no such thing as Dolby Multichannel PCM 5.1, so they need to work out why the Sonos Arc reports it as this.

It’s also clear that there is some kind of handshaking issue between LG TV’s and the Sonos Arc where it’s telling the TV it can process LPCM 7.1 but then not downmixing it properly to 5.1.

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Add my name to the plate, I’m really excited about a proper downmix from LPCM 7.1 to LPCM 5.1. I’m not angry or anything, but man…my 4K library is only half loved right now. This would certainly get me on board for some new speakers for other purposes :)

Another new Arc owner here with a 5.1 setup, and an LGC1 having this issue. 

 

I’m kind of amazed scrolling back how long this has gone on without a fix. Somewhat disheartening. 

Right? I really hope they won't let it die… it's a significant issue for many people…

I hoped they fixed it with the recent update but they didn't :(

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Perhaps its not an issue as such, and just how the lg and sonos arc report everything in LPCM as 7.1.

I must admit when the sonos arc reports something as multichannel pcm 7.1 it sounds fine to me.

i don’t have any rears though, just the ARC and Sub here.

 

In any case It would be nice if someone from support could respond, as much as I love sonos, I think their communication could be a lot better.

Well, Sonos already admitted it’s an issue. It is very noticeable when you have rear speakers. Just hope it doesn’t take as long as adding DTS support to fix this *wink*

Another new Arc owner here with a 5.1 setup, and an LGC1 having this issue. 

 

I’m kind of amazed scrolling back how long this has gone on without a fix. Somewhat disheartening. 

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Perhaps its not an issue as such, and just how the lg and sonos arc report everything in LPCM as 7.1.

I must admit when the sonos arc reports something as multichannel pcm 7.1 it sounds fine to me.

i don’t have any rears though, just the ARC and Sub here.

 

In any case It would be nice if someone from support could respond, as much as I love sonos, I think their communication could be a lot better.

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I am sure this has already been mentioned, but the Apple TV is also receiving the same issue with the audio being interpreted as Multichannel 7.1; just like my PS5. I did not have this issue with my Chromecast w/ Google TV. 

 

You would think after the CEO tweeted about a fix being in the works during this past summer, that it would be here now. I have no idea what Sonos is doing.

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So, it looks like this might be the reason: https://en.community.sonos.com/home-theater-228993/lpcm-eta-for-arc-6842558?postid=16488286#post16488286

 

TL:DR, it looks like LPCM 7.1 is downmixed incorrectly with side channels coming out the rear and rear channels not coming out at all. Back to Dolby Bitstream it is. (And back to having to switch modes between Atmos and non-Atmos on Apple TV 4k too.) Sigh.

 

I know Sonos doesn’t do ETAs, but can we at least get an official acknowledgement of this problem?

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Yeah, something is definitely wrong with the channels on Multichannel PCM. Sound coming out the wrong channels or not at all.

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Update from Sonos’ CEO on Twitter that they’re working on it:

 

https://twitter.com/Patrick_Spence/status/1334844832871682049?s=20

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Hi @ledzep1 

This has not yet been addressed. I too have seen mention that it seems to have improved - I don’t see why this would be the case (wishful thinking?).

As it counts as a new feature, rather than a bug fix, I would suggest that it will be specifically mentioned in the release notes, when it does arrive.

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Hi @ledzep1 & @Shadylane 

At present, we have no time scale to share, I’m afraid.

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Same problem with

 

Sonos Beam gen 2

LG G1

we get multichannel 7.1 instead of 5.1 in pass through mode

 

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Hi @billiejoe87 

I really strongly believe that Sonos is unintentionally misleading us with their supposed fix for this issue.

Sonos will add downconversion for LPCM 7.1 to LPCM 5.1, however I think the issue with LG TV’s incorrectly sending all LPCM audio as LPCM 7.1 won’t be fixed as it’s an LG problem. The LG’s wrongly send all LPCM as LPCM 7.1 even if it’s only LPCM 5.1 audio.

I really hope I’m wrong, but I feel Sonos announcement that the issue was on their own end has made everyone not put pressure on LG to fix their own issue with incorrectly sending the wrong audio. As someone else here said, if you use a HDFury device or a Sony TV the issue goes away. 

To be clear, I was addressing the original post, in which PCM was being selected as the output format on the source device.

If your LG TV is converting another format to 7.1 LPCM without being told to, then that is indeed an issue with the TV.

Is it really asking much for Sonos to contact LG and make them aware of the issue for all LG owners that own the Sonos Arc?

No, but it would not count as much as numerous LG TV owners getting in touch and doing the same. If we were to inform them (and perhaps we have already), but there wasn’t a significant volume of LG customers getting in touch with LG about the same issue, they wouldn’t take it as a priority. Customer contact volume is the only thing that will drive them assign the problem with a higher priority. I therefore recommend that you do get in touch with LG.

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Hi @billiejoe87 

Apologies for any confusion, but Sonos staff get trained in Sonos products, networking troubleshooting and Home Theatre troubleshooting (but only from the perspective of Sonos devices). What we don’t get is training on is the capabilities of all TV models on the market, nor XBox, PlayStation or every other kind of input device’s technical capabilities.

I interpreted the original post as an issue with 7.1 LPCM coming from the PS4, and the experience not being great. As we don’t currently support 7.1 LPCM, I suggested that this is likely to be the problem.

If you have a different kind of stream coming from an input device, and your LG TV converts that to 7.1 LPCM without being asked (and in fact converts all stream types to LPCM) then that clearly has nothing to do with Sonos, and I truly don’t know what you can do to prevent it, other than checking for TV updates and contacting LG if that doesn’t help - we have no internal documentation referring to this issue with help there for me to relay to you.

Once we support 7.1 LPCM on the Arc, I presume that this will no longer be an issue, assuming the TV does what it’s not supposed to do properly.

In the meantime, if you disable eARC on your LG TV, that will prevent it from outputting 7.1 LPCM and instead give you the same feed encapsulated within MAT or DD+, which the Arc will play without issue.

 

That’s ok @Corry P, I understand you guys are doing your best and appreciate your willingness to help. The issue is the LG OLED is one of the highest selling premium TV’s worldwide, and given the Sonos ARC is a premium sound bar designed for eARC TV’s, it is a big issue. LG Support have unfortunately over the years proven themselves to be beyond useless, so that’s likely why a lot of people are likely hoping Sonos can put pressure on them.

 

What happens is the LG TV has 2 main eARC modes that send multichannel audio. One is called “Auto” and the other “Passthrough”. It makes sense that a person would use passthrough on the TV to send through exactly what audio a device is sending the TV, through to the Sonos ARC. However this unfortunately results in any LPCM audio being sent as 7.1 regardless of whether it is LPCM 5.1 or 7.1. Other formats such as Dolby Digital and Atmos are unaffected and work properly, other than the Apple TV which seems to send everything other than Atmos as LPCM if it detects a TV or soundbar that supports LPCM.

 

The main problem with everything being sent as LPCM 7.1 is you end up with quiet audio and sound effects missing or coming from wrong speakers. I have no idea whether LG TV’s are just sending all LPCM audio in an LPCM 7.1 container and since Sonos doesn’t know what to do with LPCM 7.1, the issue is happening.

 

You can however change your LG to the “Auto” eARC mode I mentioned above which causes the TV to not send LPCM at all while still sending Dolby Digital and Atmos correctly. In this mode, all LPCM content is downconverted to Stereo which means the Sonos processes it properly. Since the Apple TV doesn’t see an LPCM compatible device, it sends audio via Dolby 5.1 and Atmos which comes out correctly. The main issue of course is that for gaming, devices like the Nintendo Switch don’t support Dolby and therefore you are stuck with Stereo. The PS4 and PS5 also have delays with Dolby Digital and many people prefer use LPCM as a result which will also just be in stereo using this mode.

 

I have chosen the latter “Auto” option personally as I would rather have stereo sound when something sends LPCM, than end up with audio coming out of the wrong channels. It however is an extremely annoying problem to have with high end equipment and one of the reasons I am returning my LG G1 for a Sony A90J as I’m not expecting the Sonos patch to fix it, the way a lot of other users seem to be.

 

I’m really bummed to see that technology in 2021 continues to not play nice together. I appreciate sonos trying to solve this problem by offering downmixing but LG should be the ones to blame here imo. I just purchased the C1 and I absolutely love this TV and my arc setup but it’s disheartening seeing this issue. 
 

@Corry P is there any update to this with regard to the feature being worked on? I understand there might not a release window yet but it’d be nice to get confirmation that this is something that is still being worked on, considering more buyers will be picking up TVs like the C1 over the holidays. Thanks. 

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Hi @billiejoe87 

Did any Sonos staff link to this thread in relation to the LG TV outputting 7.1 erroneously? If so, please let me know where.

This is a community forum and if community members, or indeed random visitors to the site, mistakenly link this thread as a complete explanation of a different issue, there’s not a lot we can do about it other than to start censoring posts (which we’re not going to do, and could only do here, not in other forums).

As 7.1 LPCM was mentioned here in relation to the Sonos Arc, and the Arc doesn’t currently support 7.1 LPCM, I reported exactly this here - I saw no need to dive any further into the issue. I did not mention LG TVs erroneously converting codecs, nor did I suggest that an update to Sonos would fix it. I simply said 7.1 LPCM is not supported on the Arc, but will be soon. At no point in the original post did the author indicate that the PS4 was outputting 5.1 LPCM while the TV was outputting 7.1. In fact, the author’s second post (first reply) brought up the “downmixing of 7.1 on Arc” subject, which is what I was replying directly to.

In addition, once the Arc does support 7.1 LCPM, I can’t see this being an issue any more - unless LG TVs are not converting to 7.1 properly (which is not something we can reliably determine before the Arc supports it). So, our update may well make the LG issue irrelevant for Arc owners, in which case waiting for the Arc update may actually be the best path forward.

 

Thank you Corry

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Hi @billiejoe87 

I certainly can see where the confusion set in. Thanks for bringing it to my attention.

Yes - If I am ever referring to a reply rather than the initial thread, I’ll likely tag the person I’m replying to, and quote their post.

I did start my post with “Hi All” due to the recent activity, but my post was in reference to the initial post. Clearly, saying “Hi All” didn’t help clarify things.

Having said that, I also thought that I was responding to the LG bug posts as well, as our fix should make it irrelevant, as mentioned in my last post.

It’s really just a software issue, so I see no reason for 7.1 downmixing support not to arrive on the Arc. As for how long it will take, I don’t have that information.

Generally, Sonos will not say anything about a feature until it’s already ready. As we’re already confirming we’re working on this, we’re committed and the Arc will downmix 7.1 LPCM at some point. The official line is “This is a feature we are currently working on, however; we do not have any further information to share with you at this time. Rest assured, we will address this in a forthcoming update.”

So, you should be good to keep your Arc beyond the return period.

Thank you for your reply. Just placed an order for an Arc :sunglasses:

I am having this same issue on the PS5.  I tried selecting the PS5 option of connecting to an AV receiver and using a 5.1 setup but I am still missing audio channels.  Anyone know what the exact issue is?

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